The invention is based on a method as generally defined hereinafter. Potentiometers have already been proposed in which in the installed state it is no longer possible to perform mechanical or optical monitoring as to whether the wiper is properly following its permitted path along the electrically conductive layer. If the movement path of the wiper deviates from the permissible one, then part of the wiper will travel over the carrier material, which is usually ceramic, and become roughened on its surface. The result is that the roughened wiper wears out the electrically conductive layer more rapidly.